1. Field of the Invention
This invention relates to a universal-type socket joint and more particularly to a dual seat ball joint.
2. Prior Art
Ball joints are well-known to the art and generally include a housing member having a cavity therein with axial openings. A ball-ended stud is received in the cavity with the ball end positioned in the cavity and the shank of the stud projecting out one of the openings. A bearing member is often received between the cavity walls and the ball end of the stud. The other opening is closed by a closure plate.
It has also been known to provide dual bearing joints having a load-carrying bearing and a load-applying bearing with a spring acting against the load applying bearing to force it against the ball end of the stud.
It has further been known to provide wear takeup capabilities in a bearing designed for use in a ball joint. Such wear takeup capabilities have included spring-urged bearings, compressible bearings and the like.
While such prior art bearings have satisfied many problems encountered in the life usage of ball socket joints, problems can arise related to the wear of the bearing surfaces and, in some instances, of the ball surface. If the bearing surface wears sufficiently, the ball can come into contact with the throat opening of the housing. When this occurs, it is possible under severe jars to the system, or as a result of further wear of the housing itself, for the ball stud to pop out of the housing. To the extent that there is still wear takeup capability in a portion of the bearing, sufficient to maintain bearing contact with the ball, this condition can occur without looseness having been noticed in the joint assembly. Thus, it is difficult for test procedures to be established which will determine when the wear condition on the interior of the joint has reached a point necessitating replacement of the joint or at least of the internal components thereof.
This problem is aggravated due to the fact that the majority of prior art joint assemblies have utilized a single-piece bearing. A single-piece bearing must, of necessity, if it is to take up wear, be formed of a relatively soft material. It would therefore be an advance in the state of the art if a bearing assembly could be constructed having a long-lasting relatively hard surface load-carrying bearing at the throat opening of the housing while at the same time having wear takeup capabilities. It would still be a further advance in the art if such a joint could have built-in limitations as to the amount of wear which it will take up or which provides means of ascertaining when sufficient wear has occurred to require replacement.